Coral reef clue to fast sea rise

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The discovery of ancient mangrove forest remains under the Great Barrier Reef has cast doubt on some theories about how quickly the sea level rose after the last ice age.

Most scientists believe it was a gradual rise over the past 9,000 years. But the existence of relic mangroves 70cm (27in) below the floor of the Barrier Reef, some with leaves and branches still intact, suggests an abrupt rise.

Dan Alongi, a biologist at the Australian Institute of Marine Science, said it appeared that sea levels rose about 3 metres in less than 30 years, drowning forests and flooding estuaries, 20 times faster than previously thought.

“Material was very much intact, it didn’t even have time to fully decompose when it was buried,” he said. “So it does tell us that when climate change last happened it was comparatively quick.”

It could indicate how quickly the climate might change in future, he said, adding that a sudden rise in sea level of the same magnitude would cause widespread damage to coastal areas.

Ocean current modelling suggests that sea levels could rise anywhere from 1cm to 10cm in the future. The Intergovernmental Panel on Climate Change says that at worst it could be 50-88cm this century

Source: The Guardian (UK)